The present invention relates to digital signal processing, and more particularly to architectures and methods for digital color video processing.
Imaging and video capabilities have become the trend in consumer electronics. Digital cameras, digital camcorders, and video-capable cellular phones are common, and many other new gadgets are evolving in the marketplace. Advances in large resolution CCD/CMOS sensors, LCD displays, and high bandwidth wireless communication coupled with the availability of low-power digital signal processors (DSPs) has led to the development of portable digital devices with both high resolution imaging and display capabilities. Indeed, various cellphone models can display digital television signals. And digital television allows for more accurate color processing than with traditional analog video, and thus capabilities such as contrast enhancement to provide the high contrast images that are appealing to human eyes. Many contrast enhancement methods have been proposed for image processing applications; but they are either too complex to be used for consumer video or still cameras, or specific for different imaging applications such as biomedical imaging.
Furthermore, digital televisions have to support traditional television systems, such as NTSC and PAL. NTSC video systems are particularly susceptible to flesh tone (skin tone, skin color) errors, because the color subcarrier in NTSC may have phase errors that cause these errors. Some tint on the flesh color due to the actual display processing requires correction, as the human eye is sensitive to flesh tones as one of the important memory colors.
CIECAM02 is a color appearance model put out by the CIE. Moroney et al., “The CIECAM02 Color Appearance Model”, IS&T/SID Tenth Color Imagining Conference, p 23 (2002) describes the conversion from usual color components (i.e., tristimulus pixel values) to the perceptual attribute correlates J, h, s of the CIECAM02 model. The model takes into account the viewing conditions to compute pixel J,h,s values.